Plant and Soil Consequences of A Long-Term Climate Change Simulation

Transcription

1 Plant and Soil Consequences of A Long-Term Climate Change Simulation Michael E. Loik, Dept. of Environmental Studies, University of California, Santa Cruz, CA 95064, mloik@ucsc.edu

2 precipitation magnitude, timing, variation tree encroachment carbon storage fire risk conservation hydrology

3 Precipitation Scenarios & Model Uncertainty Canadian Global Climate Model 1 CGCM1 Hadley Centre for Climate Prediction HadCM2 Hadley Centre for Climate Prediction HadCM3 (annual changes compared to )

4 Valentine Eastern Sierra UC Reserve, Mammoth Lakes, CA

5 For Mammoth Lakes, CA CGCM1 predicts + >100% HadCM2 predicts +80% HadCM3 predicts 10% (annual changes compared to )

6 Approach - use of 50 year old snow fences along a 50 km transect to cause snow depth forcing

7 Snow Fences - used by highway departments, ski areas, and railroads for snow control - also by water districts for water management

8 Prevailing wind accumulation ablation US Hwy 395 ca. 100 m»

9 Incorporating Climate Model Uncertainty HadCM2 predicts +80% (simulated by the snow accumulation zone) HadCM3 predicts 10% (simulated by the snow ablation zone) Prevailing wind accumulation ablation

10 N 1. June Lake (1) 2. Deadman (8) 50 km 3. MCWD (7) Mammoth Lakes, CA 4. Hot Creek (1) VESR US Hwy 395 Not to scale

11 - Inyo NF, BLM, LADWP - headwaters for Owens River (Los Angeles) - land use: recreation, grazing, timber - invasive species; fire risk - recreation: 12 million visitor days per year - increasing development and population in Mammoth Lakes

12 Hypotheses 1. Snow depth in the non-growing season affects photosynthesis during the subsequent growing season. 2. Long-term changes in snow depth (increases and decreases) alter plant community patterns. 3. Results in 1 & 2 lead to altered litter production, decomposition, and soil C and N content.

13 snow depth soil water content photosynthesis community structure ANPP litter quality, quantity root production SOM surface CO 2 flux decomposition N mineralization

14 Control zone Depth = D Accumulation zone Depth = ca. 2D Ablation zone Depth = ca. 0.7D Snow fence Control plots Snow fence Accumulation plots Ablation plots N 100 m 100 m 100 m 50 m 10 m 35 m 5 m 5 m 5 m Prevailing wind direction

15 Hypothesized Response Response control +snow -snow Location (assuming that snow depth impacts soil water content, community patterns, and ecosystem processes.)

16 Hypotheses 1. Snow depth in the non-growing season affects photosynthesis during the subsequent growing season. 2. Long-term changes in snow depth (increases and decreases) alter plant community patterns. 3. Results in 1 & 2 lead to altered litter production, decomposition, and soil C and N content.

17 snow Snow depth (cm) ambient -snow Transect distance (m) February, 2004

18 April, 2004 following snowmelt Soil moisture (% by wt) a ab b control +snow -snow Location

19 Artemisia tridentata (Asteraceae) Great Basin Sagebrush Purshia tridentata (Rosaceae) Antelope Bitterbrush

20 Location 0-1 Water potential (MPa) a ab b Artemisia tridentata, P = 0.09 a a b Purshia tridentata, P = 0.03 upwind +snow -snow

21 Stomatal conductance (mmol m -2 s -1 ) Artemisia tridentata Purshia tridentata control +snow -snow Location

22 Location CO 2 assimilation (μmol m -2 s -1 ) Artemisia tridentata Purshia tridentata control +snow -snow

23 Hypotheses 1. Snow depth in the non-growing season affects photosynthesis during the subsequent growing season. 2. Long-term changes in snow depth (increases and decreases) alter plant community patterns. 3. Results in 1 & 2 lead to altered litter production, decomposition, and soil C and N content.

24 Species Richness 10 a Species richness ab b 2 0 Up Acc Abl Location One-way ANOVA: F = 2.84, P = 0.09

25 Relative Cover Artemisia tridentata Purshia tridentata Relative % cover Up Acc Abl Location

26 70 60 Artemisia tridentata Purshia tridentata Relative % cover Up Acc Abl Decreased albedo on snow plots? Location

27 a P = b c control +snow -snow Location Leaf area index (unitless)

28 a b? c control +snow -snow Location Leaf area index (unitless)

29 going to reproduction? Leaf area index (unitless) a control +snow -snow b going to wood? snow pressure? c going to roots/soil? snow mold? Location

30 Albedo upwind +snow -snow Location

31 Hypotheses 1. Snow depth in the non-growing season affects photosynthesis during the subsequent growing season. 2. Long-term changes in snow depth (increases and decreases) alter plant community patterns. 3. Results in 1 & 2 lead to altered litter production, decomposition, and soil C and N content.

32 Mortality (shrub skeletons) Artemisia tridentata higher mortality on -snow plots Purshia tridentata no difference

33 b b a control +snow -snow Location Coarse woody debris (m per 100 m)

34 Soil C and N (to date) - organic C is higher in ambient, compared to +snow and snow plots - higher at 10 compared to 30 cm depth - no differences for nitrogen content

35 snow depth yes soil water content yes photosynthesis somewhat, ongoing root production litter quantity, quality SOM yes albedo No community structure surface CO 2 flux decomposition N mineralization

36 Winter eight months of snow 57 cm SWE at fences (25 feet on Tioga Pass)

37 Soil Organic Matter Work in Progress Litter production Decomposition

38 Work in Progress - need to examine potential for fertile island effect Do C, N, and other nutrients vary under the canopy of A. tridentata or P. tridentata, compared to open, inter-canopy sites?

39 Work in Progress Soil moisture & temperature probes at 10, 25, 50, 75, and 100 cm depth Bulk density, NPK, roots, SOM

40 Work in Progress Seasonal water relations, gas exchange, LAI, NDVI, albedo From snowmelt (May) to dormancy (Sept?) 2005

41 Annual growth rings + snow 13 C reconstruction of long-term WUE - snow

42 Many thanks Alden Griffith, Holly Alpert, Dan Dawson and the Valentine Eastern Sierra Reserve staff, David and Jody Holl M. Theo Kearney Foundation for Soil Science Inyo National Forest

43 Snow fence complex Number snow fences Elev (m) Soil Depth Vadose Zone (cm) Infiltration rate (cm h -1 ) June Lake Cozetica > Deadman Vitrandic Xerorthent; Cryopsammet Mammoth Haypress > Hot Creek Torriothentic Haploxeroll >

44 Snow depth (cm) Average monthly precipitation (mm) sd -2 sd Time Jan Feb Mar Apr MayJun Jul Aug Sep Oct NovDec Month